radiation

And perhaps as significant as radiation in the long term is time spent away from Earth's gravity.

While gamma rays are not uncommon in space, radiation of this magnitude had only been observed in distant galaxies.

But space is a hostile environment for the human body, with high levels of radiation, something both sperm and egg cells are highly sensitive to.

Scientists monitor climate change using the Earth's energy imbalance – the difference between the solar energy entering the Earth's atmosphere and the radiation going back out into space.